Dramatic images going wide for the first time tell a surprising tale of Martian eruptions. The pictures doing the dazzling today were shot by the Mars Reconnaissance Orbiter (MRO) in 2010 and show the predictable — if beautiful — rusty dunes of the Martian surface, sculpted like snowdrifts from the planet’s tenuous but persistent wind. The scene is broken up, however, buy strange, black, spidery blemishes scattered randomly about. From orbit they look tiny, but on the ground they’d be huge — surely larger than a football field. It’s partly their very ugliness that makes them eye-catching and partly the mystery of what causes them. Actually, however, that last part is likely no mystery at all — and the source of the features is one more indication of how complex a planet Mars is turning out to be.